The Republican presidential primary debate provided plenty of fireworks Thursday night, a stark contrast to the two more sleepy affairs earlier this year. Michele Bachmann and Tim Pawlenty took off the gloves and threw several punches at one another. Ron Paul and Rick Santorum nearly screamed at each other over whether to prevent Iran from obtaining a nuclear weapon. And Newt Gingrich didn't like some of the questions thrown his way, which he angrily denounced as "Mickey Mouse games."

The key exchanges were between Bachmann, a congresswoman from Minnesota, and Pawlenty, Minnesota's former governor, who are in a battle to see who can come out ahead of the other in a key straw poll vote Saturday in Ames.

For weeks, the two had been bashing one another, mostly on the campaign trail here in Iowa. Bachmann has claimed the title of Iowa frontrunner, while Pawlenty has been playing catch up in advance of Saturday's straw poll. Fox News' Chris Wallace was quick to give the two an opportunity to fight it out in person.

Pawlenty, whose argument has been that he has the executive experience as a governor that Bachmann lacks, said the congresswoman has "done wonderful things in her life, absolutely wonderful things, but it's an indisputable fact that in Congress her record of accomplishments and results is nonexistent. That's not going to be good enough."

As Pawlenty, whose fiber was questioned after he failed to take on Mitt Romney in the last debate, delivered his rebuke, he turned to face Bachmann, but turned away after a few moments. Bachmann, in her response, faced Pawlenty the entire time she spoke. She blasted his record as governor.

"Governor, when you were governor in Minnesota, you implemented cap and trade in our state, and you praised the unconstitutional individual mandate, and you called for requiring all people in our state to purchase health insurance," she said. She also dinged him for saying in 2006 that "the era of small government is over."

"That sounds a lot more like Barack Obama if you ask me," she said as Pawlenty shook his head.

The two went back and forth for a few more minutes, with Bachmann lauding her own record of fighting Democratic proposals, such as President Obama's health care overhaul as well as cap and trade legislation. But Pawlenty, growing more animated, said that she had failed to stop the health care bill, as well as increases in spending and the 2008 bailout of Wall Street banks, which was actually implemented under Republican President George W. Bush.

The two sparred again minutes later over a cigarette tax passed in 2005 that Bachmann voted in favor of and Pawlenty signed. Bachmann said she voted for it only because it was attached to an anti-abortion measure. She accused Pawlenty of cutting deals with special interests, while Pawlenty said her statements were "illogical."

The consensus afterward among the pundits and campaign operatives was that Bachmann came out on top, in part because her response was so strong and in part because Pawlenty came across as too negative. Kent Sorensen, a Republican state legislator who is supporting Bachmann, certainly felt that way.

"She exposed [Pawlenty] for the phony that he is," Sorensen said. "He came out with the first punch and she came back with a roundhouse."

Moments after each exchange, Bachmann campaign staff circulated through the press room, handing out detailed press releases attacking Pawlenty's record and detailing why Bachmann voted for the cigarette tax.

Clearly, Bachmann was prepared for the incoming fire. She entered the night in a dramatically different position than she had nearly two months ago at her first debate. That night, in New Hampshire, she announced her candidacy, introduced herself and her biography to voters and impressed observers with her poise.

Thursday night she had a large target on her back and much more to lose.

Before the debate began, some Iowa Republican insiders expressed doubt about the extent to which she has had time to organize for the straw poll, and said expectations for her performance Saturday may be too high. Her debate performance will likely do nothing to dampen her support and could give her more.

However, even if she wins the straw poll, or finishes a close second, she will face a newly-formed threat in the form of Texas Gov. Rick Perry. Perry's impending entry into the race was confirmed several hours before the debate by a spokesman in Texas. It was timed in such a way that it was almost impossible for the moderators of the debate to avoid asking the eight candidates on stage about the soon-to-be candidate.

But Bachmann was the only frontrunner asked about him, and that was only in passing.

"I think there is room in the race for Sarah Palin, Rick Perry or even Bret, you too," she said to Fox News' Bret Baier.

Perry has registered in second place in some national poll numbers out just this week, behind former Massachusetts Gov. Mitt Romney. Some have speculated that he will immediately become the frontrunner in the race, displacing or threatening Romney, who had a shaky moment on the stump at the Iowa State Fair earlier in the day on Thursday. Questioned aggressively by Iowans during his appearance at the Des Moines Register "soapbox," Romney grew agitated. His line that "corporations are people" was the moment that headlined news dispatches, but it was the level of emotional volatility -- the picture of him yelling at voters -- that might prove just as damaging.

At the very least, Perry has the potential to steal Bachmann's thunder with grassroots conservatives and Tea Party voters. He can match her charisma. And he has a lengthy track record in Texas that is certainly full of vulnerabilities but also boasts a topline achievement of having created more than a third of all new jobs in the U.S. since 2009.

Bachmann had already signaled earlier Thursday, before Perry's office made his entry semi-official, that she sees him as a direct competitor. Her campaign announced that she would attend the same Black Hawk County Republican dinner in Waterloo on Sunday afternoon where Perry is scheduled to make his debut in the Hawkeye State.

Perry's entrance, as complicating as it might be for Bachmann, is probably more troubling for Pawlenty -- another candidate who has been trying to catch up to Bachmann in Iowa and must do well in the straw poll Saturday to even sustain his campaign, at least in its current form and size.

It was the first debate for Jon Huntsman, the former U.S. ambassador to China and Utah governor. He entered the night needing, at the very least, to make a memorable first impression with Republican primary voters. But he did little to stand out.

Romney was in some ways an afterthought, in part because he has downplayed the importance of Iowa, and as a result expectations for him here are lower. But the other candidates were often so busy fighting with one another that, again, he went unscathed. Afterward, his campaign immediately announced that he had "won the debate."

Pawlenty was asked whether he still believes Romney's health care reform in Massachusetts was similar to Obama's federal plan, but the exchange lacked punch. It did spark a fascinating exchange about how each candidate views the extent to which states are sovereign and have the ability to impose things on their citizens. Paul, a Texas congressman, stated a broad view of states' rights, while Santorum, a former senator from Pennsylvania, said that the 10th amendment discussion had "run amok."

Santorum said that if a state wanted to make polygamy legal, that should not be allowed.

"I respect the 10th Amendment, but we are a nation that has values," he said. "States don't have the right to tramp over those because of the 10th Amendment."

One of the other most intense exchanges was an extended back and forth between the same two men.

Paul said he did not have a problem with Iran trying to obtain nuclear weapons.

"Why wouldn't it be natural that they might want a weapon ... Why should we write people off?" he asked. "What's so terribly bad about this?"

Santorum was aghast.

"Iran is not Iceland, Ron. Iran is a country that has been at war with us since 1979," he said.

Paul said that the U.S. has meddled in Iran since the CIA was involved in the 1953 coup of Iran's democratically elected prime minister.

The two went another round, which ended with Paul nearly screaming about the "trillions" of dollars spent on foreign wars. As usual, a loud contingent of fans cheered him on.

Gingrich, the former House Speaker from Georgia, was also animated in denouncing the so-called "super committee" appointed by Congress to reduce the deficit by $1.5 trillion, calling it "as dumb an idea as Washington has come up with."

He also didn't like some of the questions thrown his way about the departure of large numbers of his staff earlier this year, and told Wallace so.

"I took seriously [fellow host] Bret [Baier]'s injunction to put aside the talking points. I wish you would put aside the gotcha questions," he said, to some ooos and ahhhs.

Gingrich then went on to compare himself twice to Ronald Reagan, who had staff departures during his run for the White House in 1980.

Wallace didn't take it lightly. "If you think questions about your record are Mickey Mouse, I'm sorry," he said, with disdain. "I think those are questions people want to hear answers to."